There is an ever increasing demand for inexpensive and environmentally acceptable viscosifiers, bioemulsifiers and biodegradable polymers. The biotechnology industry has responded with increasing the availability of a variety of bacterial cell products that may find their way into commercial use. Although many of the bacterial products offer a wide range of attractive improvements over synthetically produced materials, they remain relatively expensive to produce. The expense is generally associated with costs of recovery and purification of the desired product.
Higher yields of biopolymers are the result of a better understanding of biosynthesis and optimization of fermentation conditions. This satisfies one of the important steps in recovering adequate amounts of the polymer for potential industrial applications. Nonetheless, recovery of these polymers remains a difficult and costly step. Recovery of a biopolymer, regardless of the conditions used to produce it, typically involves a precipitation step; the precipitated biopolymer is recovered by centrifugation.
There are two major inefficiencies associated with a typical recovery protocol. The first problem arises if significant numbers of the producing population are killed by the precipitation protocol. The viable biomass must then be reinoculated and allowed to equilibrate to the conditions optimal for the recovery of the biopolymer. These steps require the addition of nutrients and energy that increase the cost of producing the biopolymer. Another major inefficiency is incomplete recovery of the biopolymer of interest. Different bacterial exopolymers are attached to (or associated with) the producing cells with varying degrees of tenacity. Those bacteria that have relatively securely attached exopolymers are less likely to shed them into the medium, thus reducing the amount of exopolymer available for recovery in the precipitation step.
The compositions of the present invention have demonstrated their ability to significantly increase the recovery of exopolymer from a microbial culture. The materials do not apparently affect the amount of exopolymer produced by the bacterial cells, but serve only to increase the efficiency of exopolymer recovery.